Facing a stalemate at the bargaining table with the management of four Chicago International Charter Schools, the Chicago Teachers Union on Wednesday staged an act of “civil disobedience” by blocking entrances and elevators in a prominent Loop high-rise.

The building, at 1 N. Wacker, is home to the London-based accounting firm PricewaterhouseCoopers. A partner in the Chicago office, Laura Thonn, is the board president of Chicago International, or CICS, which oversees 14 charter schools in Chicago through a network of five smaller management groups.  

Related: Multiple layers, multiple CEOs: Strike puts charter management under microscope

The teachers’ union has made the group’s complex organization chart a central focus in the strike. On Tuesday, CTU President Jesse Sharkey filed a formal complaint letter with the state’s newly elected attorney general, Kwame Raoul, claiming that he was “troubled” by $19 million in management fees that the union has claimed the charter operator invested with the firm of a former board president and treasurer, an investment manager named Craig Henderson, who runs his own firm.

“Depending on when Henderson’s firm first began to provide investment services,” the letter reads, “his firm may have received hundreds of thousands of dollars from the foundation over which Craig Henderson has held considerable power and influence.” Read the full letter below.

“Our findings suggest self-dealing and conflicts of interest at the highest levels of a non-profit organization operating charters schools across 14 school sites in Chicago,” it concludes.

The union cannot bargain over management structure. The sticking points at the bargaining table are pay for teachers and paraprofessionals, class size, and the length of the school day.

The charter network did not immediately respond to requests for comment about the complaint letter. But a spokeswoman from CICS told Chalkbeat Wednesday afternoon that if Civitas, which manages the four schools under strike, agreed to the union’s current demand of 105 percent of the teacher salary schedule for district-run schools, it would be bankrupt within three years.

“CICS is obligated, out of fairness to each of its 8,300 students, to allocate resources equitably to all 14 campuses, which means that any additional funds CICS provides to Civitas, they also have to provide increased funding proportionally to the other 10 campuses.”

In advance of Wednesday’s action, the CEO of the overarching charter network, Elizabeth Shaw, sent an email to staff and board members with the subject line “potential disruption” and urging them to treat the striking teachers “with respect and compassion.”  

“Please recognize that these are teachers that educate CICS children at our CICS schools,” she wrote. “While we may have disagreements over what is in the best interest of our schools, it is their right to peacefully demonstrate.”

About 180 teachers and support staff from four schools are on strike. About 2,200 children are affected, though schools are open and staffed by non-union employees.

Following Wednesday’s two hour sit-in, three members of the bargaining team went upstairs to present their letter to a member of Pricewaterhouse’s marketing division. “Our issues have been heard, after nearly 40 of us were willing to risk arrest,” said bargaining team member and CICS Northtown high school teacher Jen Conant.

The union’s chair of the charter division, Chris Baehrend, issued a warning that the current strike could spur others. “CTU still has 13 charter schools in negotiations — there could be seven more strikes before June,” he said. “The charter industry needs to change the way it operates.”